The Decennial Census Digitization and Linkage (DCDL) Project is an initiative to digitize and link individual respondent records from the decennial censuses of 1960 through 1990. The DCDL project will complete a massive longitudinal data infrastructure covering almost the entire U.S. population since 1940.
While the Census Bureau has microdata files from the 1960 through 1990 censuses, those files have never included respondent names and were therefore never linked over time. Names from these censuses are only available on the microfilmed images of the original census manuscripts, in the respondents’ own handwriting. The DCDL project is digitizing the microfilm-based census manuscripts, recovering handwritten names, and creating anonymous linkage keys allowing researchers to link individual respondent records over time.
Access & Timeline
The data from the DCDL project will become part of the Census Bureau’s data linkage infrastructure. This infrastructure allows researchers to link all files anonymously at the person-level on approved projects within the Federal Statistical Research Data Centers (FSRDCs). FSRDC researchers can currently request linked data from the censuses of 1940 and 2000-2020. The 1960-1990 Census data resulting from the DCDL project will be available as soon as it is complete, most likely by the end of 2026.
Impact
The DCDL will complete an infrastructure including individual-level linked data across eight decennial censuses. The resulting multi-purpose resource will create new and transformational opportunities for research, education, and evidence-building across the social, behavioral, and health sciences.
To take one significant example, DCDL data will provide the data backbone for the American Opportunity Study (AOS). Led by researchers at Opportunity Insights, the AOS is using a wide range of data to examine long-term neighborhood-level variation in economic opportunity and mobility.
The AOS is emblematic of the ground-breaking social science research and public policy evaluation that will be possible through the Census Bureau’s data linkage infrastructure as a result of the DCDL. A significant portion of DCDL funding comes from the urgent need for better historical data to support this type of research.
